The present invention relates to a backup system for a personal computer (hereinafter referred to as a “PC”), and more particularly to a backup system for a computer system wherein a plurality of PCs employ storage areas in a storage device via a network.
A magnetic disk storage device (hereinafter referred to as an “HDD”) is used to store data obtained by a computer. In order to prepare for a case wherein these data are lost or damaged, the computer makes a copy of data stored on the HDD and transfers the copy to a second HDD. This data protection process is generally called a backup. Normally, when backing up data for a PC, a user manually designates for the backup a source HDD and a destination HDD, and initiates the backup process and copies data at a specific time. As another method, a backup process for data stored on a specific HDD is written as a shell script and periodically performed.
Recently, a network type storage device (hereinafter simply referred to as a storage device) that can be connected to a computer has become available because use is made of a network, such as an iSCSI or a Fibre Channel (FC). In a computer system that uses a storage device, each computer employs storage areas (Logical Units: LUs) obtained by logically dividing the storage device, instead of the HDD of the computer (hereinafter referred to as a “local HDD”).
One backup method for the LU of a storage device is proposed, for example, in US2005/0086443A1. According to US2005/0086443A1, the storage device automatically backs up the LU at a date and time as designated by a user. Furthermore, when the computer employed is a server computer, a manager systematically controls the booting/shutdown of the computer and the start/end of an application, thereby enabling the designation of an appropriate backup date and time.
In a computer system wherein a plurality of PCs employ the LUs of a storage device via a network, the booting/shutdown of the PCs and the start/end of an application are performed irregularly, or the LUs are employed by a user for an extended period of time. Therefore, even when a backup execution date and time previously designated by a user are reached, the LUs provided for the storage device may still be used.
According to a conventional method, when an LU is still being employed, no means is available for detecting this, and the storage device starts the backup process when the backup date and time are reached. However, since I/O activity is continued for the LU, the backup process can not be performed.